Field
The present invention relates to an improvement of electrostatic discharge (ESD) resistance of a field-effect transistor (FET) used in a microwave band/millimeter wave band.
Background
In recent years, application of GaN-based FET amplifiers featuring high withstand voltage, high output and low thermal resistance to microwave/millimeter wave hands is progressing in the fields of mobile phone base stations, satellite communication amplifiers and radar amplifiers. However, although the GaN-based FETs exhibit sufficiently high two-terminal and three-terminal withstand voltage characteristics compared to conventional GaAs-based FETs, in terms of liability to failures caused by ESD (static electricity discharge), the resistance of the GaN-based FETs cannot be said to he sufficiently high. For example, ESD resistance of GaN-based FETs often has been proven to be on the order of 250 to 500 V according to human model (HBM) tests. In assembly of semiconductor devices and in actual use after mounting on printed circuit boards, minimizing ESD malfunction generally requires resistance of 1 kV or higher in HBM tests. In not only GaN-based FETs but also conventionally used GaAs-based FETs, insufficient ESD resistance (resistance to ESD-caused malfunction) often has been questioned in actual use.